Add a tool to detect invalid formatting in localized strings

tools/VerifyTranslatedStringFormatting.java

@@ -0,0 +1,116 @@
+// run: java tools/VerifyTranslatedStringFormatting.java
+// Reads all localized strings and makes sure they contain valid formatting placeholders matching the original English strings to avoid crashes.
+
+import org.w3c.dom.*;
+import javax.xml.parsers.*;
+import java.io.*;
+import java.util.*;
+import java.util.regex.*;
+
+public class VerifyTranslatedStringFormatting{
+	// %[argument_index$][flags][width][.precision][t]conversion
+	private static final String formatSpecifier="%(\\d+\\$)?([-#+ 0,(\\<]*)?(\\d+)?(\\.\\d+)?([tT])?([a-zA-Z%])";
+	private static final Pattern fsPattern=Pattern.compile(formatSpecifier);
+
+	private static HashMap<String, List<String>> placeholdersInStrings=new HashMap<>();
+	private static int errorCount=0;
+
+	public static void main(String[] args) throws Exception{
+		DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
+		factory.setNamespaceAware(false);
+		DocumentBuilder builder=factory.newDocumentBuilder();
+		Document doc;
+		try(FileInputStream in=new FileInputStream("mastodon/src/main/res/values/strings.xml")){
+			doc=builder.parse(in);
+		}
+		NodeList list=doc.getDocumentElement().getChildNodes(); // why does this stupid NodeList thing exist at all?
+		for(int i=0;i<list.getLength();i++){
+			if(list.item(i) instanceof Element el){
+				String name=el.getAttribute("name");
+				String value;
+				if("string".equals(el.getTagName())){
+					value=el.getTextContent();
+				}else if("plurals".equals(el.getTagName())){
+					value=el.getElementsByTagName("item").item(0).getTextContent();
+				}else{
+					System.out.println("Warning: unexpected tag "+name);
+					continue;
+				}
+				ArrayList<String> placeholders=new ArrayList<>();
+				Matcher matcher=fsPattern.matcher(value);
+				while(matcher.find()){
+					placeholders.add(matcher.group());
+				}
+				placeholdersInStrings.put(name, placeholders);
+			}
+		}
+		for(File file:new File("mastodon/src/main/res").listFiles()){
+			if(file.getName().startsWith("values-")){
+				File stringsXml=new File(file, "strings.xml");
+				if(stringsXml.exists()){
+					processFile(stringsXml);
+				}
+			}
+		}
+		if(errorCount>0){
+			System.err.println("Found "+errorCount+" problems in localized strings");
+			System.exit(1);
+		}
+	}
+
+	private static void processFile(File file) throws Exception{
+		DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
+		factory.setNamespaceAware(false);
+		DocumentBuilder builder=factory.newDocumentBuilder();
+		Document doc;
+		try(FileInputStream in=new FileInputStream(file)){
+			doc=builder.parse(in);
+		}
+		NodeList list=doc.getDocumentElement().getChildNodes();
+		for(int i=0;i<list.getLength();i++){
+			if(list.item(i) instanceof Element el){
+				String name=el.getAttribute("name");
+				String value;
+				if("string".equals(el.getTagName())){
+					value=el.getTextContent();
+					if(!verifyString(value, placeholdersInStrings.get(name))){
+						errorCount++;
+						System.out.println(file+": string "+name+" is missing placeholders");
+					}
+				}else if("plurals".equals(el.getTagName())){
+					NodeList items=el.getElementsByTagName("item");
+					for(int j=0;j<items.getLength();j++){
+						Element item=(Element)items.item(j);
+						value=item.getTextContent();
+						String quantity=item.getAttribute("quantity");
+						if(!verifyString(value, placeholdersInStrings.get(name))){
+							// Some languages use zero/one/two for just these numbers so they may skip the placeholder
+							// still make sure that there's no '%' characters to avoid crashes
+							if(List.of("zero", "one", "two").contains(quantity) && !value.contains("%")){
+								continue;
+							}
+							errorCount++;
+							System.out.println(file+": string "+name+"["+quantity+"] is missing placeholders");
+						}
+					}
+				}else{
+					System.out.println("Warning: unexpected tag "+name);
+					continue;
+				}
+			}
+		}
+	}
+
+	private static boolean verifyString(String str, List<String> placeholders){
+		for(String placeholder:placeholders){
+			if(placeholder.equals("%,d")){
+				// %,d and %d are interchangeable but %,d provides nicer formatting
+				if(!str.contains(placeholder) && !str.contains("%d"))
+					return false;
+			}else if(!str.contains(placeholder)){
+				return false;
+			}
+		}
+		return true;
+	}
+}